The Crookes radiometer is an early-model infrared-radiation and light-detector. A variant type of this is the Nichols radiometer that operates on a different principle, and is more sensitive than the Crookes type. These two models are very early versions of mm-wave radiometers.
To obtain a high quality mm-wave radiometric picture, a very stable mm-wave imaging system is needed. There are some well known stabilisation methods, developed in 1960's for radio astronomy. One solution is to stabilize the mm-wave imaging system by adding a well known noise-signal, like e.g. a noise insertion radiometer.
A noise insertion radiometer consists of a Dicke-radiometer wherein a switch switches between a mm-wave antenna signal and an internal noise signal.